The linked essay makes perfect sense to me; and I'm certain the only reason it doesn't to you is indeed just the jargon. I don't think it's a particularly good analysis, ultimately, but for boring reasons that would make any essay weak, not because it's saying nothing. It's also not attempting to be a knock-down argument, not on account of its theoretical stance, but because it's a short blog post firing off some impressions in a perhaps unjustifiably confident tone, which of course Manly Man Rational Economists(tm) do all the time.

That said, my acquired intuition is that within [the cluster of people/ideaspace that the typical LessWrong reader would ugh-field as "pomo"], as within many other clusters, the lack of clarity in language does certainly covary with lack of clarity in actual thought. But I can't really say how much my own tribal academic loyalties (or desire to believe that I can understand anything that means anything) have helped produce that sensation.